The present invention relates to ventilation systems for residential structures and more particularly to such a system which provides automatic initiation and adjustment of exhaust fan operation.
Heretofore most whole house and attic ventilation systems have been operated either manually or by simple thermostats. While such systems can reduce requirements for air conditioning, their operation is often relatively uncontrolled and does not provide any adjustment for differing circumstances such as changing outdoor temperature and/or changes in internal thermal loading. While variable speed fans have been proposed heretofore, they have largely been designed for industrial and/or agricultural environments and the mode of operation was not well adapted to residential structures.
Among the several objects of the present invention may be noted the provision of a novel system for ventilating residential structures; the provision of such a system which employs a variable speed exhaust fan; the provision of such a system which adjusts fan speed as a function of exhaust air temperature to maintain a desired temperature within a living space; the provision of such a system whose operation is inhibited when the temperature of the external environmental air is not low enough to appropriately cool an inside space; the provision of such a system which utilizes controlled hysteresis to avoid unstable operation; the provision of such a system which minimizes acoustical noise; the provision of such a system which saves electrical energy; the provision of such a system which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.